Effect of the Addition of Rare Earth Element La on the Tribological Behaviour of AlSi5Cu1Mg Alloy

The effects of 0, 0.3, 0.6 and 0.9 wt % modifier La on the dry sliding wear behaviours of AlSi5Cu1Mg alloy were investigated under different friction conditions (normal loads, sliding velocities) by using pin-on-disc configuration. The microhardness of the alloys was tested, and it was found that the microhardness of the alloys was improved by the La addition. The AlSi5Cu1Mg + 0.6 wt % La alloy exhibited the smallest grain size and maximum microhardness. The wear mechanism analysis of the worn surface was done, which drew support from a scanning electron microscope (SEM) that was equipped with an energy dispersive spectrometer. The results showed that AlSi5Cu1Mg + 0.6 wt % La alloy exhibited the best wear resistance, which was mainly due to the modified grain and microhardness. At the sliding velocity of 0.19 m/s, the adhesive wear became the main wear mechanism with the increase of the load because of the rupture of the oxide layer on the friction surface. Under the load of 3.8 MPa, the abrasive wear became slight as the sliding velocity increasing, due to the recrystallization phenomenon that happened in the frictional surface.